The invention relates primarily to a process for adjusting the composition of the combustible mixture supplied to an internal combustion engine by means of the admission of a supplementary quantity of air via a bypass line to the intake system of the internal combustion engine.
This broad concept has been disclosed heretofore, for example, by the German laid-open application No. 24 31 046. There a throttle device provided in an air bypass line is controlled by means of the throughput dependent suction tube subpressure in the most constricted cross-sectional area of the carburetor venturi, for the apportionment of the supplementary air introduced into the suction tube of an internal combustion engine to supplement the operating mixture delivered by the carburetor for the internal combustion engine. A regulating apparatus with which the pressure obtained at the venturi of the carburetor is modified is additionally superimposed on this air bypass quantity control for the regulation of the compositon of the operating mixture. However, this subpressure is not large enough in some of the operating regions of the internal combustion engine to achieve a reliable and accurate positioning of the throttle device as a dependent function of the air throughput or the operating mixture throughput of the internal combustion engine.